Examine source code of YouTube WatchGuard

{
  "manifest_version": 2,
  "name": "YouTube WatchGuard",
  "version": "1.0",
  "description": "Control the amount of time you spend on YouTube",
  "permissions": [
    "storage",
    "tabs",
    "*://www.youtube.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon.png",
      "48": "icon.png",
      "128": "icon.png"
    }
  },
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{13022908-6aa0-4d7b-9351-17d3872149df}"
    }
  }
}